1. Field of the Invention
The present invention generally relates to a reciprocating piston type refrigerant compressor, and more particularly, the present invention relates to an improvement in the discharge valve mechanism incorporated in the reciprocating piston type refrigerant compressor.
2. Description of the Related Art
The conventional reciprocating piston type compressor is provided with a plurality of either single headed pistons or double-headed pistons reciprocating in the associated cylinder bores to implement suction, compression and discharge of the refrigerant gas. The compressed gas discharged from the cylinder bores is delivered to an air-conditioning system or a climate control system of, for example, an automobile. The reciprocation of the pistons is caused by the rotation of a swash plate or the non-rotating nutating motion of a wobble plate which is driven by the rotation of the drive shaft. The discharge of the compressed gas from the respective cylinder bores is controlled by a discharge valve mechanism. The discharge valve mechanism includes discharge ports formed in an end wall (usually, a valve plate) covering an end of each of the respective cylinder bores, a discharge chamber formed in a housing or housings and communicating with the respective cylinder bores for receiving the compressed gas discharged from the cylinder bores, a discharge valve assembly having a plurality of integrally formed reed-valves, and a valve retainer assembly for retaining the respective reed-valves at the respective opening positions thereof. The discharge valve assembly and the valve retainer assembly are held in the interior of the compressor either by an appropriate fixing means or by being attached to a wall portion of the housing.
FIG. 5 illustrates a typical arrangement of one part of the conventional discharge valve mechanism of the reciprocating piston type compressor. As shown in FIG. 5, the discharge valve mechanism arranged between a housing "A" and a valve plate "B" includes a discharge port "b" formed in a valve plate "B". The discharge port b is covered by a reed-valve "d" movable from an opening position backed up by a valve retainer "a" toward its closing position in contact with a valve seat "C" of the valve plate "B" to close the port "b". The valve retainer "a" is held between the housing "A" and the valve plate "B", and provided with a support portion gradually curving away from the valve seat "C" into the discharge chamber defined in the housing "A". The support portion of valve retainer "a" backs up the entire portion of the rear face of the reed valve "d". A flow passage defined between the port "b" and the reed valve "d", moved to its opening position, is so narrow that the compressed gas discharging into the discharge chamber from each cylinder bore through the flow passage is subjected to a large resistance. Namely, the discharging of the compressed gas consumes considerable power, and accordingly, the power for driving the compressor must be large. The large power requirement results in the application of a large load to a drive source such as an automobile engine.
Further, the use of the retainer "a" is not desirable from the viewpoint of reducing the number of parts or elements necessary for assembling the reciprocating piston type compressors. Moreover, since the retainer "a" is usually produced by plastic deformation of a metallic plate, the dimensional accuracy of the retainer "a" is low due to the spring back of the metallic plate. Thus, the retainer "a" is unable to accurately determine an opening position of the discharge reed valve "d".